Block-signal system.



No. 869,865. PATENTED 001. 29. 1907.

L. A. HAWKINS. BLOCK SIGNAL SYSTEM.

APPLICATION FILED MAR. 28, 1908.

Wfzfnesses;

five/760x" zyg E Laurence A. Haw/rims W 4/ Atty,

UNITED STATES PATENT OFFICE.

"LAURENCE A. HAWKINS,"OF soHENEcTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC- GOMPANY, A CORPORATION OF NEW YORK.

BLOCK-SIGNAL SYSTEM.

Specification of Letters Patent.

Patented Qct. 29, 1907 Application filed Maroh 28.1908. Serial ms. 303,433.

vented certain new anduseful Improvements in Block- Signal Systems, of which the following is a specification,

My invention relates to block signal systems for electrically-operated roads employing the rails as return conductor for the power-current. It has been proposed heretofore to provide such road s'with alternating-current signal systerns, since by the use of alterna'ting-currents the signal system may be so arranged as not to be interfered'with by' direct power-current or by alternating power current of different frequency. The general arrangement that has been proposed heretofore comprises means for supplying alternating-curre'nt'tother'ails of a block and an inductive winding connectedto the signal endoi the block. This induct.

ive winding maybe the. primary of a transformer, the

secondary of-which supplies the track relay, or it may .be a reactance coil shunting the track relay; the winding in either case being formed of a conductor large enough to .carry'the power-current, and having sufiicientreactance so as notto act as a short-circuit for the high irequency alternating signal-current. Adjacent blocks are connected so as to' form a path for the power 'current. This connection" is preferably formed between. equipotential points with respect to the signal current,-that is, from the central point of ,the inductive winding. before mentioned. With this connec tion the power-current in the two portions of the inductive winding on opposite sides of-the connection is in opposition, so that the signal-current and powercurrent pass through the same conductors without interierence. This connection and the results obtained thereby 'are' fully explained in Patents Nos. 645,907 and 647,741, issued to Bedell, March 20, 1900, and Apri1 17, 1900, respectively 'and need not he further discussed here.

" A signal system as'briefl'y outlined above has been found to be satisfactory as far assingletracks are concerned. It sometimes happens, however, in the case r i of roads having parallel tracks that it is desired to crossbond thetwotracks so as to improve the conductivity of the system for-the power-current. The addition of such cross c'onnections between the ends oi parallel blocks introduces certain ditiiculties whichit is the object of the present invention' to remove, These difliculties arise from the fact that since the two parallel blocks are electrically connected in parallel, a

railon one block may be broken without, causing the signal for-that block to go todanger, since the parallel blo'ck serves as a shunt around the broken rail This is Obviously a source pf danger.

My invention consists in inserting between a cross connection and a 'rail of a block, signal-controlling means whereby the signal may be caused to go to danger when thecontrolling means is denergized. Since the signal controlling means is inserted between the cross-connection and the rail it will always bedsituergized when that rail is broken, whether current is flowing through the cross-connection to the other rail 'or not. Consequently, a broken rail will always be protected and the signal set automatically at danger.

My invention will best be understood by reference to the accompanying drawing, which shows diagram-' mat ically a block signal system for electrically-opelated roads arranged in accordance with. my invention.

In-the drawing A and A represent the rails of two parallel'bloeks of a double-track road.

B and B represent the supply conductors for the power-current.

The block A' is supplied with alternating-current by A means ofa transformer O, the primary of which is connecteddirectly or through a step-down transformer to the alternating current supply-conductors D. A transformer E has its primary connected to the opposite end of the block, and its secondary supplies a coil F of the track relay. This relay is shown as of the polyphasc induction type, the other primary coil G being supplied directly or through a transformer from the alternatingcurrent line-wires D. Such-a relay is wholly unaff'ected by an unbalanced fluctuating power-current in the primary of the transformer E. The short-circuitcd secondary member H of the relay carries a contact adapted to close a circuit through the source of current I and the operating mechanism J of a signal K. This operating mechanism is illustrated diagrammatically, as it forms no part of my present invention.

L Lrepresent relays which may be of the ordinary solenoid type inserted between the primary transformer winding E and the rails of the block.

A connection is made from the central points of the secondary of transformer G and of the primary of transformer E to corresponding points on adjacent blocks. Through these'c'onnections the power-currcntis transmitted, normally passing in opposite directions and in substantially equal amounts through two parts of the transformerwinding on each side of the connection. Furthermore; cross connections between the two tracks are made as shown in the drawing, so as to bond the two tracks together, thereby improving the general conductivity of the system. Without these cross-com nections," it is obvious that a break in one rail of the block A, as, for instance, at X, would prevent the flow of current in any portion of the block, and would consequently put the signal K at danger, since the relay coil F would be denergized. With the cross-connections,

however, this is no longertrue. For instance, with a.

break at X current may flow from the central, point of the secondary of transformer-Cthrough the cross-connection to the opposite track, through the two portions of the primary of transformer E in opposite. directions, through the two rails A in parallel, through the tWO portions of the secondary of transformer G iuopp S t directions, through the cross-connection to the central former E, induces an el'ectromotive force in the second-- ary winding, which energizes relay F and may hold the relay in position to keep thesignal Kat clear. .In order to prevent such a contingency, the-relays L L' are'marrangement of parts here ployed. One of these relays is inserted between the cross-connection from the opposite track and each of the rails of the block A. These relays'are normally held in the position shown by the alternating signal-current. They may be of the simple solenoid type, since the only effect of the power-current is to hold the relay contacts more firmly closed. 'The only requisite in the design of these relays is that their windings shall be of large enough cross-section to carry the power-current, and atthe same time that the relays shall be sensitive enough to be held closed by the alternating signal-current,

Since both relays L L are energized only when curren is flowing through both rails, it is evident that if either rail breaks, one of the relays will be denergized, since 111 that case neither signal-current nor power-current can pass through it. Thus, for instance, if a brealgoccurs at X the upper relay L w-ill bedenergized, there by breaking the circuit of the relay winding F seas to cause the relay to open the signal-operating circuit and put the signal at danger. The contacts of both relays L are in series with the Winding F so that if either relayis denergized, the signal will go to danger.

Obviously, the contacts of the relays L may he included in any other circuit, which, when opened, will put the signal at danger. Furthermore, these relays may be of any desired construction, instead of the simple solenoid type shown. Consequently, I do not desire to limit myself to the particular construction and shown, but aim in the 'appended claims to cover all modifications which are and a rail of the block.

within the scope of my invention. 3

What I claim as new, and desire to secure by'Letters Patent of the United States, is,

1. In a signal system for electrically-operated roads having parallel tracks and employing the rails as return conductor for the power-current, means for supplying alternating-current to the rails of a block, an inductive winding connected across the rails at 'oneend of the block, a

cross-connection between said block and a parallel blockadapted to form a path for the power-current, and signal controlling means inserted between said cross-connection 2. In a. signal system for electrically-operated roads having parallel tracks and employing the railsas return conductor for the power-current, means for supplying alternating-current to the rails of a block, an inductive winding connected across the rails at one end of the block, a cross-connection between said blockand a parallel block adapted to form a path for the power-current, a

seases the last-mentioned winding.

3. In a signal system for electrically-operated roads" having parallel tracks and employing the rails as return, ,cgnductor for the power-current, means-iofsupplying alternating-current to the rails of a blocl'rgan inductive Winding connected across the rails at one end of the block, across-connection between said blockand a parallel block adapted to form a path for the power-current, a winding inserted between said connection: and a rail of the block, a signal for the block, and controlling means for the si nal controlled by the current in fthela'st-mentioned wlnd ing. 1 p

4.1m a signal -system for electrically-operated ,roads having parallel tracks'and employing the rails as return conductor for the powencurrent, means for supplying" alternating-current. to -the railsof a block, an inductive winding connected across .the rails at one end of the block, a cross-connection betweensaid block and a pan,

alleiblock adapted to form a path fortli'e power-current,

a relay Iyvinding inserted betweensaid connection. and

rail of the block; a signal for the block, whereby said signal is caused said relay is, deis'ndrgified.

'5. In a signal system for e1ectrically operated.- roads employing the rails .as return conductor. for tii'e'r'powerand connections to'indicate danger when current, means for su plying alternatingcurrent-to the rails of a block, aninductive' windlng connected across th v rails atone endoi the block, a connection-from. the central point Of'Sillfl winding to an adjacentlblock adapted to at;

ford fa path'for thenower current. aridsig''na'l-controlii 11g es with said winding on 'acli;side of said means in ser connection,

. 6. 11; a signal systm ifor elctrically operated roads employing-the rails as return COliflUCEOi f0l the powercurrent, means for supplying alternating-current to the rails of a'block, .a tr ansformer having its primary connected across the rails atone end 'of the block,' a connectlon Im'mthe central point ofsaidprimary to adjacent blocks adapted to' affords patn for the'power-current,a

signal-controlling relay supplied from the secondary of said transformer, and[signal-controlling means in series [with the primaryon eacn side or said-connectlon.

7. In asignal'wsystem for electrlcally operated roads employing the rails as return conductor for. the powercurrent, means for supplying alternating-current" to the rails of a'block, an inductive winding connected across the rails at'one end of the block, acon' nection from the central point'of said winding'to adjacentibiocks adapted to afiforda path, for the power-current, two windings in series with the first on opposite sides of said connection, a signal, and means for causingv the signal to indicate danger upon a failure of current in either of said two vwindings.

- 8. In a signal system for electrically-operated roads employing the rails as return conductor for the power current, means for supplying alternating-current to" the rails of a block, aninductive winding connected across the rails at one end of the block, a connection from the central point of said winding to adjacent blocks adapted to aiford a path for the power-current, two windings in series with said inductive winding on opposite sides or said connection, a signal, and controlling means for said signal controlled by the current in ea'chof said two'windings.

.9. Ina signal system for electrically-operated roads em ploying the rails as return conductor'for the power-current, means for supplying alternating-current to the rails of a block, an inductive winding connected across the rails at one end of the block, a connection from the central point of said winding to adjacent blocks adapted to afford a path for the power-current, two relays in series with said winding on oppdsite sides of said connection,-.a.signal,

and connections whereby said signal is caused to indicate 7 danger when either of said'relays is dele'nergized.

10. In a signal system for electrically-operated roads employing the rails as return conductorfor .the powercurrent, means for supplying alternating-current to the rails of a block, an inductive windingconnected across the rails at one end of the block, a connection from the cen- 12. In 21 signal system for electricnllycperated roads 15 tral point ofsaid winding to adjacent blocksndnpted to I having parallel tracks,- a connection between unend of a afiord a path for the power-current, two relays in series i block and the parallel track adapted to form it path for with said winding on opposite sides of said connection, a signal, a circuit passing through the contacts of both relays, and means in said circuit for causing said-signal to indicate danger when said circuit is broken.

11. In .a signal system for electrically-operated roads having parallel tracks, a connection from :in cm] of :1 block to the parallel track adapted to form a path for the power-current, a relay winding inserted between said c011 the power-current, independent windings inserted between said connection and the rails of the block, independent relay contacts controlled by the current in said windings 20 respectively, a signalfor the block, and operative connections between both relay contacts and the signal.

In witness whereof, I have hereunto set my hand this 20th day of March, 1906.

LAURENCE A. HAWKINS. Witnesses BENJAMIN B. HULL, HnLnN OBI-0RD. 

